Strictly speaking, Cora would have a vested interest in making sure no live Lancelot showed up to raise the issue of who was running the haven.
But you never know.
True, but she might not be above stowing him away in dungeon or tower somewhere, 'cause that's just how evil fairytale queens roll . . .
I mean, if you just want to get rid of someone, there are probably easier ways than curses and poison apples and endless naps that can only be broken by true love's kiss or whatever. But evil queens never just whack someone when they can curse them instead.